High thermal shock resistance fused-cast zirconium mullite brick and preparation method thereof

Abstract

The present invention discloses a fused-cast zirconium mullite brick with high thermal shock resistance and a preparation method thereof, relating to the technical field of refractory materials. The technical solution is as follows: The brick comprises the following components in percentage by mass, calculated as oxides: Al2O3 75-78%, SiO2 15.5-18%, ZrO2 2-3%, Fe2O3 2-3%, and TiO2 0.4-1.2%, with a Fe2O3 to ZrO2 mass ratio of (0.95-1.05):1, and the sum of the mass percentages of Na2O, K2O, CaO, and MgO is less than 1%. Furthermore, the fused-cast zirconium mullite brick has a columnar structure. While maintaining the high refractoriness under load of the fused-cast mullite brick, the present invention solves the problems of poor thermal shock resistance and the susceptibility of large-sized fused-cast zirconium mullite bricks to breakage due to kiln temperature fluctuations during manufacturing, kiln heating, and use.

Description

Technical Field

[0001] The invention relates to the technical field of refractory materials, in particular to a fused-cast zirconium-mullite brick with high thermal shock resistance and a preparation method thereof. Background Art

[0002] Fused-zirconium-mullite bricks, characterized by high wear resistance and a high refractoriness under load, are widely used in metallurgical pusher-type heating furnaces and in the titanium sponge smelting industry. As these high-temperature industrial kilns grow in size, large-scale fused-zirconium-mullite bricks are susceptible to breakage, flaking, and even collapse during manufacturing, heating, and operation due to temperature fluctuations in the kiln, seriously impacting the continuity and stability of kiln production.

[0003] Chinese invention patent CN1044083A discloses recycled fused-cast refractory bricks and a method for manufacturing them. It discloses a technical solution for using fused-cast refractory bricks (waste bricks) used in glass kilns as raw material. The waste bricks are sorted, coarsely crushed, finely crushed, magnetically separated for iron removal, and sieved to reduce the particle size to 0.5-30 mm. The melting process parameters are then improved to produce the regenerated fused-cast refractory bricks. This solution addresses the issues of unstable chemical composition and high porosity associated with recycled waste bricks, reducing production costs by over 50%. However, the product in the embodiment of the invention has a high ZrO2 content, resulting in poor thermal shock resistance.

[0004] Chinese invention patent CN102241521A discloses a high-temperature wear-resistant brick and its casting method. The method uses raw materials such as bauxite clinker, kaolin clinker, synthetic mullite, zircon sand, desiliconized zirconium, primary industrial sodium carbonate, and calcite. By adjusting dopants such as sodium oxide and calcium oxide, it facilitates the formation of an intercrystalline glass phase, minimizing the degradation of the product's wear resistance. The patent adds 0.9-1.2% Na2O and limits the Fe2O3+TiO2+CaO+MgO content to 0-5%. Although the patent does not investigate the wear resistance, thermal shock resistance, and refractoriness under load of the prepared brick, the introduction of a large amount of glass phase to improve wear resistance may reduce the brick's thermal shock resistance or refractoriness under load.

[0005] Chinese invention patent CN114573342A discloses a method for preparing fused-cast refractory products and the products produced therefrom. The method involves heating the raw materials to 2100-2200°C in an electric melting furnace or a three-phase electric furnace for melting, injecting the melted liquid into a refractory product mold cavity placed in an insulation box, and then naturally cooling the material. When the temperature cools to 1750-1680°C, the insulation box is vibrated up and down to produce the fused-cast refractory product. The patented preparation method can achieve a relatively concentrated distribution of the glass phase, preventing it from forming a network, thereby blocking the distribution of the mullite phase or the cubic or tetragonal zirconia phase, improving the performance of the mullite refractory product or the zirconia refractory product, and solving the problem of the glass phase component in the fused-cast mullite brick seeping into the glass melting furnace, thereby contaminating the products in the glass furnace. However, vibration during the solidification process of the liquid can easily damage the refractory product mold and cause the liquid to leak.

[0006] In summary, it is necessary to develop a fused-cast zirconium mullite brick with high thermal shock resistance to solve the problem of poor thermal shock resistance and to meet the increasingly stringent requirements of the industrial field for refractory materials, which is of great significance. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology, provide a fused-cast zirconium mullite brick with high thermal shock resistance and a preparation method thereof, and solve the problems of poor thermal shock resistance and easy breakage of large-sized fused-cast zirconium mullite bricks due to temperature fluctuations in the kiln during manufacturing, heating and kiln baking, and use while maintaining a high load refraction temperature of the fused-cast zirconium mullite bricks.

[0008] The technical solution of the present invention is:

[0009] On the one hand, the present invention provides a fused-cast zirconium mullite brick with high thermal shock resistance, which includes the following components in mass percentage, calculated as oxides: Al2O3 75-78%, SiO2 15.5-18%, ZrO2 2-3%, Fe2O3 2-3%, TiO2 0.4-1.2%, the mass ratio of Fe2O3 to ZrO2 is (0.95-1.05):1, the sum of the mass percentages of Na2O, K2O, CaO and MgO is less than 1%, and the microstructure of the fused-cast zirconium mullite brick is columnar.

[0010] The Fe2O3 component promotes the formation of uneven, coarse crystallization particles, increases the glass phase, and lowers the glass phase's exudation temperature. Therefore, activated carbon is used as a reducing agent to reduce the Fe2O3 content in bricks. Approximately 0.225 kg of activated carbon is required to reduce 1 kg of iron. Excessive activated carbon addition inevitably reduces excessive SiO2, affecting the amount of mullite formed. Based on a 75-78% Al2O3 and 15.5-18% SiO2 content, the present invention eliminates the need for a reducing agent to reduce the Fe2O3 content. Instead, the Fe2O3:ZrO2 mass ratio is controlled to a 0.95-1.05:1 ratio. This promotes the formation of relatively complete columnar crystals of mullite and corundum, reducing cracking in the product and significantly improving the product's 1100°C thermal shock resistance test results. Furthermore, the ZrO2 component increases the viscosity of the glass phase, improving the product's chemical stability and its resistance to erosion and erosion by molten glass.

[0011] Preferably, the microstructure of the fused-cast zirconium mullite brick is columnar mullite crystals, corundum crystals or mullite-wrapped corundum crystals, with a crystal length of ≥30 mm and a width of <3 mm.

[0012] On the other hand, the present invention provides a method for preparing the above-mentioned fused-cast zirconium mullite brick with high thermal shock resistance, comprising the following steps:

[0013] S1 batching: mixing raw materials to form batch;

[0014] S2 Melting and Clarification: Melt the batch material at 2000-2200℃ and then clarify it. After clarification, cool it to 1810-1900℃ to obtain a melt;

[0015] S3 casting: pouring the melt into the mold;

[0016] S4 annealing: burying the model in a hollow ball and then performing annealing treatment;

[0017] S5 cutting and grinding process can produce fused-cast zirconium mullite bricks with high thermal shock resistance.

[0018] Preferably, in step S2, melting and clarification are carried out in a three-phase electric arc furnace, with a melting current of 4200-4400A and a melting voltage of 170-190V.

[0019] The high melting current not only significantly shortens the melting time of raw materials and improves production efficiency, but also creates a more uniform high-temperature field, ensuring that the various components of the raw materials are fully mixed and reacted at the molecular level, reducing the component segregation phenomenon from the root and improving product consistency.

[0020] Preferably, the clarification current is 2100-3000A, and the clarification voltage is 121-150V. Fine clarification of the liquid can effectively remove impurities and bubbles, greatly improving the purity and density of the product.

[0021] Preferably, in step S3, the casting speed is 5-8kg / s. The casting temperature of 1810-1900°C and the casting speed of 5-8kg / s ensure that the slurry fills the mold under the best fluidity and solidification characteristics, avoiding molding defects caused by improper temperature. The model used for casting is made of resin combined with silica sand, and the surface is covered with zircon powder coating. Among them, the silica sand is high-quality silica sand with SiO2>99.5wt.%, and the resin uses ZJC-F-XA resin from Zibo Juyun Casting Materials Co., Ltd., and the addition amount is 3wt.%; the zircon powder coating uses ZJC-ST-003N coating product from Zibo Juyun Casting Materials Co., Ltd., and the coating thickness is 0.5mm. This model effectively controls the collapse time of the sand mold while ensuring the strength of the sand mold.

[0022] Preferably, in step S4, the hollow sphere is formed by forming a silicon-aluminum clay material and sintering it at a temperature above 1400°C, and its density is less than 0.8g / cm 3 , and its chemical composition is Al2O3>40wt.%, SiO2<55wt.%, Fe2O3<2wt.%, MgO<2wt.%.

[0023] The unique thermal insulation and cushioning properties of the silicon-aluminum hollow spheres used in this invention ensure uniform heating of the blank during the annealing process, minimizing internal stress and ensuring effective annealing. This results in a more uniform internal stress distribution within the product, improving thermal shock resistance and casting yield. After annealing, the surface temperature of the blank in the mold remains below 100°C.

[0024] Preferably, the silica-alumina clay material is prepared from raw bauxite, scorched earth, Datong soil and Laiwu soil.

[0025] Preferably, in step S4, the annealing temperature is 1810-1900° C., and the annealing time is ≥180 h.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The highly thermal shock-resistant fused-cast zirconium-mullite bricks prepared by the present invention, by controlling the melting process and the content of each component, can form a structure with an alternating distribution of columnar mullite crystals, corundum crystals, or mullite-encased corundum crystals. They can withstand over 21 1100°C thermal shock tests without flaking. While maintaining the high refraction-under-load temperature of the fused-cast mullite bricks, the present invention addresses the problems of poor thermal shock resistance and the susceptibility of large-sized fused-cast zirconium-mullite bricks to breakage due to kiln temperature fluctuations during manufacturing, kiln heating, and use.

[0028] 2. The high heat shock resistance fused-cast zirconium mullite brick of the present invention has a structure with staggered distribution of columnar crystals, which makes it have the advantages of high strength, high load softening temperature, high thermal shock resistance, and a qualified rate of large-size products of more than 95%, which has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a photograph of the organizational structure of the fused-cast zirconium mullite brick prepared in Example 1 of the present invention. In the figure, ① is columnar mullite crystals, corundum crystals or mullite-wrapped corundum crystals, and ② is a glass phase.

[0030] Figure 2 This is a photograph of the organizational structure of the fused-cast zirconium mullite brick prepared in Comparative Example 1 of the present invention. In the figure, ① is columnar mullite crystals or corundum crystals, ② is glass phase, and ③ is granular mullite crystals or corundum crystals. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0032] In the following examples and comparative examples, Al2O3, SiO2, and Fe2O3 were derived from bauxite clinker, coke clinker, iron bauxite, alumina powder, zircon sand, and fused AZS waste bricks; ZrO2 was derived from zircon sand and fused AZS waste bricks; and TiO2, Na2O, K2O, CaO, and MgO were derived from impurities introduced into the above raw materials. All of the above raw materials were commercially available, and the chemical composition test results of each raw material are shown in Table 1:

[0033] Table 1 Chemical composition test results of each raw material

[0034]

[0035] The preparation method of the fused-cast zirconium mullite brick in the following embodiment comprises the following steps:

[0036] S1: Weigh all raw materials and put them into a cone mixer to mix evenly to form a batch;

[0037] S2 Melting and Clarification: Place the batch material into a three-phase electric arc furnace, adjust the current to 4200-4400A, the melting voltage to 170-190V, and heat to 2000-2200℃ for smelting to ensure that the raw materials are completely melted and the components are evenly mixed; after the smelting is completed, reduce the current to 2100-3000A, the clarification voltage to 121-150V, and clarify the resulting liquid to remove impurities and bubbles. The clarified liquid is then cooled to 1810-1900℃ to obtain a melt;

[0038] S3 casting: pour the molten metal into the mold, paying attention to controlling the casting speed evenly. The mold sizes are 300mm×600mm×1100mm and 300mm×600mm×400mm respectively, and the casting speed is 5-8kg / s;

[0039] S4 annealing: After casting, the model is embedded in a hollow ball made of silicon-aluminum material and annealed at 1810℃-1900℃ for at least 180h. After annealing, the surface temperature of the blank in the model is lower than 100℃. The hollow ball made of silicon-aluminum clay is formed by sintering at 1400℃ and its density is less than 0.8g / cm 3 , and its chemical composition is Al2O3>40wt.%, SiO2<55wt.%, Fe2O3<2wt.%, MgO<2wt.%; the silica-alumina clay material is made of raw bauxite, charcoal, Datong soil and Laiwu soil in a mass ratio of 1:1:1:1;

[0040] S5 Cutting and Grinding: Take out the blank and use cutting and grinding equipment to process it according to the preset size and precision requirements to obtain high heat shock resistant fused-cast zirconium mullite bricks.

[0041] The qualified rate statistics of the prepared fused-cast zirconium mullite bricks and the microstructure test of the bricks were carried out on products with a size of 300mm×600mm×1100mm.

[0042] The performance test of the prepared fused-cast zirconium mullite bricks was carried out. The test blocks used were cut from products with a size of 300mm×600mm×400mm. The position and size of the cut samples were in accordance with the provisions of "JCT 493-2015 Fusion-cast zirconium corundum refractory products for glass melting furnaces". The performance test methods are as follows: bulk density and apparent porosity are measured in accordance with GB / T2997-2015 Test method for bulk density, apparent porosity and true apparent porosity of dense shaped refractory products; room temperature compressive strength is measured in accordance with GB / T 5072-2008 Test method for room temperature compressive strength of refractory materials; thermal shock resistance is measured in accordance with GB / T 30873-2014 Test method for thermal shock resistance of refractory materials; refractoriness under load is measured in accordance with YB / T2203-1998 Test method for refractoriness under load of refractory castables (non-differential-heating method); chemical composition is measured in accordance with GB / T 21114-2019 Method for X-ray fluorescence spectrochemical analysis of refractory materials - Cast glass disc method.

[0043] Examples 1-7

[0044] The components of the high thermal shock resistant fused-cast zirconium mullite bricks of Examples 1-7 are shown in Table 2, the process parameters during the preparation process are shown in Table 3, and the performance test results are shown in Table 4.

[0045] Table 2 Composition of high thermal shock resistant fused-cast zirconium mullite bricks of Examples 1-7

[0046]

[0047] Table 3 Process parameters of high thermal shock resistant fused-cast zirconium mullite bricks of Examples 1-7

[0048]

[0049] Table 4 Performance test results of high thermal shock resistance fused-cast zirconium mullite bricks of Examples 1-7

[0050]

[0051] The components of the fused-cast zirconium mullite bricks of Comparative Examples 1-9 are shown in Tables 5-6. The process parameters of Comparative Examples 1 and 4 are the same as those of Example 1, the process parameters of Comparative Examples 2 and 8 are the same as those of Example 2, the process parameters of Comparative Examples 3 and 5 are the same as those of Example 5, and the process parameters of Comparative Examples 6 and 7 are the same as those of Example 6. The process parameters of Comparative Example 9 differ from those of Example 1 in that the melting current is 3500 A, the melting voltage is 150 V, the clarification voltage is 111 V, the melt temperature is 1800° C., and the annealing time is 150 h.

[0052] Table 5 Components of the fused-cast zirconium mullite bricks of Comparative Examples 1-5

[0053]

[0054] Table 6 Composition of the fused-cast zirconium mullite bricks of Comparative Examples 6-9

[0055]

[0056] The organizational structure photos of the fused-cast zirconium mullite bricks prepared in Example 1 and Comparative Example 1 are as follows: Figure 1-2 , Figure 1 It shows that columnar mullite crystals, corundum crystals or mullite-wrapped corundum crystals ① in Example 1 are alternately distributed in the glass phase ②. The width of the crystals is about 2 mm and the length is about 36 mm. Figure 2 It is shown that in Comparative Example 1, columnar mullite crystals or corundum crystals ① and granular mullite crystals or corundum crystals ③ are scattered in the glass phase ②, and the main crystal form is columnar mullite crystals or corundum crystals ①, with a width of about 1 mm and a length of about 3 mm; the width and length of the granular mullite crystals or corundum crystals ③ are both about 3 mm.

[0057] The performance test results of the fused-cast zirconium mullite bricks of Comparative Examples 1-9 are shown in Tables 7-8.

[0058] Table 7 Performance test results of fused-cast zirconium mullite bricks of comparative examples 1-5

[0059]

[0060] Table 8 Performance test results of fused-cast zirconium mullite bricks of comparative examples 6-9

[0061]

[0062] It can be seen from Table 4 that the fused-cast zirconium mullite bricks prepared in Examples 1-7 of the present invention have a crystal length greater than 20 mm, a room temperature compressive strength greater than 380 MPa, and a 1100°C thermal shock resistance test number greater than 20 times.

[0063] It can be seen from Tables 2, 4, 5 and 7 that the Fe2O3 and ZrO2 contents in Comparative Example 1 and Example 1 are both within the range of 2-3%, and the mass ratios of Fe2O3 to ZrO2 are 0.98:1 and 0.99:1, respectively, which are very close, and the process parameters are consistent. However, the Al2O3 content in Comparative Example 1 is 79%, resulting in a crystal length of only 3 mm in the product structure prepared therefrom, only 6 thermal shock tests at 1100°C, and a refractoriness under load temperature of only 1670°C. It is speculated that this is because the Al2O3 content in Comparative Example 1 is too high, and corundum crystals are formed first during cooling, followed by mullite and corundum eutectoids. During the crystallization process, the number of corundum nuclei in the slurry is large, and the crystals are difficult to grow, thereby affecting the thermal shock resistance and refractoriness under load of the fused-cast zirconium mullite brick.

[0064] It can be seen from Tables 2, 4, 5, and 7 that the mass ratio of Fe2O3 and ZrO2 in Comparative Example 2 is close to that in Example 2, and the process parameters are consistent. However, the Al2O3 content in Comparative Example 2 is 74.3%, resulting in the product structure prepared therefrom being mainly granular crystals with a crystal length of 4 mm, the number of thermal shock tests at 1100°C is only 9 times, and the refractoriness under load is 1693°C. It is speculated that because the Al2O3 content in Comparative Example 2 is relatively low, the number of mullite and corundum eutectoids formed during cooling is large, which is difficult to grow, forming a product structure dominated by granular crystals, thereby affecting the thermal shock resistance and refractoriness under load of the fused-cast zirconium mullite brick.

[0065] As can be seen from Tables 2, 4, 5, and 7, the Al2O3 content in Comparative Example 3 is similar to that in Example 5, the mass ratio of Fe2O3 to ZrO2 is close, and the process parameters are consistent. However, the SiO2 content in Comparative Example 3 is 14.74%, resulting in a crystal length of only 6 mm in the product prepared therefrom, 7 times of thermal shock resistance test at 1100°C, and a room temperature compressive strength of only 265 MPa. It is speculated that because the SiO2 content in Comparative Example 3 is too low, the amount of glass phase in the fused-cast zirconium mullite brick is small, and the crystals cannot fully grow, resulting in a high apparent porosity, low compressive strength, and poor thermal shock resistance of the fused-cast zirconium mullite brick.

[0066] As can be seen from Tables 2, 4, 5, and 7, the Al2O3 content in Comparative Example 4 is similar to that in Example 1, and the contents of Fe2O3 and ZrO2 are both within the range of 2-3%. The process parameters are consistent, but the SiO2 content in Comparative Example 4 is 18.3%, resulting in a crystal length of 8 mm and a width of 4 mm in the product prepared therefrom, and the number of thermal shock tests at 1100°C is only 6. It is speculated that because the SiO2 content in Comparative Example 4 is too high, the amount of glass phase in the fused-cast zircon-mullite brick is large, resulting in the crystals developing into plate-like shapes and failing to form a staggered distribution structure. This results in an extremely low apparent porosity of the fused-cast zircon-mullite brick, but a refractoriness under load temperature of only 1663°C.

[0067] As can be seen from Tables 2, 4, 5, and 7, the Fe2O3 content in Comparative Example 5 is 3.85%, the granular main crystals in the product produced are 4 mm in length and 4 mm in width, and the number of thermal shock tests at 1100°C is 11. It is speculated that because the Fe2O3 content in Comparative Example 5 is too high, iron oxide is dissolved into the corundum and mullite crystals, and the crystals develop into granular forms. This results in a high apparent porosity of the fused-cast zirconium-mullite brick and a refractoriness under load temperature of only 1687°C.

[0068] As can be seen from Tables 2, 4, 6, and 8, the contents of Al2O3, SiO2, and ZrO2 in Comparative Example 6 and Example 6 are similar, and the process parameters are consistent. However, the Fe2O3 content in Comparative Example 6 is 1.82%, resulting in the main granular crystals in the product prepared being 4 mm long and 2 mm wide, and the number of 1100°C thermal shock resistance tests being 8. It is speculated that because the Fe2O3 content in Comparative Example 6 is too low, the corundum crystallization and mullite crystallization interfere with each other during growth, resulting in the crystals developing into fine granules, resulting in low room temperature compressive strength of the fused-cast zirconium mullite brick, with a refractoriness under load temperature of only 1682°C.

[0069] As can be seen from Tables 2, 4, 6, and 8, the ZrO2 content in Comparative Example 7 is 1.71%, resulting in the main granular crystals in the product being 4 mm in length and 4 mm in width, and the number of thermal shock tests at 1100°C being only 5. It is speculated that because the ZrO2 content in Comparative Example 7 is too low, the viscosity of the glass phase is low, causing the corundum and mullite crystals to develop into granular crystals, resulting in low room temperature compressive strength of the fused-cast zirconium-mullite brick.

[0070] As can be seen from Tables 2, 4, 6, and 8, the ZrO2 content in Comparative Example 8 is 4.44%, the granular main crystals in the product prepared therefrom are 4 mm in length and 4 mm in width, and the number of thermal shock tests at 1100°C is 8. It is speculated that due to the excessively high ZrO2 content in Comparative Example 8, the viscosity of the glass phase is high, and the corundum and mullite crystals develop into granular forms, resulting in poor thermal shock resistance of the fused-cast zirconium-mullite brick.

[0071] Tables 2, 4, 6, and 8 show that Comparative Example 9 exhibits lower melting current, melting voltage, and clarification voltage than Example 1, resulting in a product with crystals measuring 6 mm in length and 2 mm in width. The product passed the 1100°C thermal shock test only once, exhibited severe cracking, and had a pass rate of only 22%. This is attributed to the inability to effectively remove impurities and bubbles during clarification in Comparative Example 9, resulting in significant temperature differences between different regions of the feed solution and the resulting significant thermal stress in the product.

Claims

1. High thermal shock resistance fused-cast zirconium mullite brick, characterized by: Calculated as oxides, the brick comprises the following components in mass percentage: Al2O3 75-78%, SiO2 15.5-18%, ZrO2 2-3%, Fe2O3 2-3%, TiO2 0.4-1.2%, the mass ratio of Fe2O3 to ZrO2 is (0.95-1.05):1, the sum of the mass percentages of Na2O, K2O, CaO and MgO is less than 1%, and the microstructure of the fused-cast zirconium mullite brick is columnar; the microstructure of the fused-cast zirconium mullite brick is columnar mullite crystals, corundum crystals or mullite-encapsulated corundum crystals, with a crystal length of ≥30 mm and a width of <3 mm; A method for preparing a fused-cast zirconium mullite brick with high thermal shock resistance comprises the following steps: S1 batching: mixing raw materials to form batch; S2 Melting and Clarification: Melt the batch material at 2000-2200℃ and then clarify it. After clarification, cool it to 1810-1900℃ to obtain a melt; S3 casting: pouring the melt into the mold; S4 annealing: burying the model in a hollow ball and then performing annealing treatment; S5 cutting and grinding process, that is, the fused-cast zirconium mullite brick with high thermal shock resistance is obtained; In step S2, melting and clarification are carried out in a three-phase electric arc furnace with a melting current of 4200-4400A and a melting voltage of 170-190V; a clarification current of 2100-3000A and a clarification voltage of 121-150V.

2. The high thermal shock resistance fused-cast zirconium mullite brick according to claim 1, characterized in that: In step S3, the casting speed is 5-8 kg / s.

3. The high thermal shock resistance fused-cast zirconium mullite brick according to claim 1, characterized in that: In step S4, the hollow sphere is formed by forming a silicon-aluminum clay material and sintering it at a temperature above 1400°C, and its density is less than 0.8g / cm 3 , and its chemical composition is Al2O3>40wt.%, SiO2<55wt.%, Fe2O3<2wt.%, MgO<2wt.%.

4. The high thermal shock resistance fused-cast zirconium mullite brick according to claim 3, characterized in that: The silica-alumina clay material is prepared from raw bauxite, scorched gemstone, Datong soil and Laiwu soil.

5. The high thermal shock resistant fused-cast zirconium mullite brick according to claim 1, characterized in that: In step S4, the annealing temperature is 1810-1900° C., and the annealing time is ≥180 h.

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